DE1224934B - Method and device for the production of polycrystalline metal hair - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. CL:

C22b

German class: 40 a - 5/20

Number: 1224 934

File number: Sch 36084 VI a / 40 a

Filing date: November 10, 1964

Opening day: September 15, 1966

It is known that coagulation (aggregation of colloidal particles into aggregates) consists of Metal colloids, which represent ferromagnetic elementary areas, in gases with extremely large Speed takes place and that this creates chains of elementary crystallites. Such chain-like Coagulation is the cause of a random by-product in the manufacture of iron powder by the decomposition of iron carbonyl and create matted masses, so-called iron wadding. It attempts have been made to deliberately produce similar cellular aggregations by collecting applied magnetic fields to win rod-shaped magnetic materials, for example for sound carriers. However, these known methods are not suitable for producing any length or thickness, to produce homogeneously structured metal hairs, as they are due to the unhindered growth of the originally very small primary metal colloids to merge more or less large granular ones Lead aggregations.

The invention has set itself the task of producing polycrystalline metal hairs in a predetermined length and thickness from the gas phase, which are characterized by extraordinary strength. To solve this object is achieved according to proceed so that first carbonyls ferromagnetic metals in an oxygen-free, filled, for example, with inert gases space in the smallest quantities, on the order of 10- ⁴ to 1O ^-10 moles per cm ⁸ of this space towards one in this space generated temperature gradient are fed in, whereby the metal atoms released by the thermal decomposition of the carbonyls agglomerate to the smallest crystallites, which are arranged by a homogeneous magnetic field in aggregation chains parallel to each other and to the lines of force of the magnetic field, which are mechanically stabilized by the magnetic field, whereupon in Carbonyls of ferromagnetic and / or paramagnetic metals are fed into the room and passed through the room against the temperature gradient, while at the same time adjusting the temperature of the aggregation chains to the temperature required for a coherent separation of these metals, until the metal hairs are the desired thickness.

In this way it is possible to produce metal hairs which have a very large ratio of diameter to length, for example up to 1: 100,000 and above, and in which the diameter of the hair to the diameter of the coagulation chain is in a ratio of up to 1,000,000: 1 and above are available method and apparatus for the production of
polycrystalline metal hair

Applicant:

Hermann J. Schladitz,
Munich 19, Ruffinistr. 12-14

Named as inventor:
Hermann J. Schladitz, Munich

can. This structure of the individual metal hairs can be used, for example, by sintering manufactured materials receive previously unattained strength values.

Further details and features of the invention emerge from the following description in FIG Connection with the drawings, in which, for example, devices for carrying out the invention Procedure are shown.

In the device according to FIG. 1, a reaction vessel 1 is a gas-permeable, but electrical insulated heating surface 2 and opposite this an evaporation or exit source 3 arranged for the gaseous metal compounds, so that a temperature gradient from the surface 2 to Source 3 can be generated. The source 3 has pores which allow the metal compounds to emerge with even, if possible, non-turbulent flow. The interior of the reaction vessel 1 is subject to the influence of a magnetic field which is directed parallel to the heating surface 2. This magnetic field is as homogeneous as possible within the extension of the heating surface 2 and can be passed through in Magnetic poles 4 and 5 arranged at a suitable distance or generated by a magnetic coil.

After the interior of the reaction vessel 1 has been flushed out in a known manner by means of oxygen-free gases and is filled and the temperature of the heating surface 2 has been brought to a value that is essential is above the temperature of complete decomposition of the metal carbonyls, e.g. B. for iron pentacarbonyl to a temperature between 250 and 350 ° C,

so the reaction chamber of the vessel 1 is obtained from the source 3, a very small amount of metal carbonyls, in the order of 10 ~ ⁴ to

609 660/338

Mol per cm ^{3 of} the decomposition space supplied. Since any turbulence due to flow is avoided when the metal carbonyl is fed into the reaction space, the metal carbonyl reaching the heating surface 2 against the temperature gradient is decomposed on a broad front, with the precipitation of metal atoms that form ferromagnetic crystallites in an extraordinarily short time also form into chain-like aggregations in an extremely short time. The amount of metal carbonyl initially decomposed is such that it is only in a ratio of 1:10 ⁴ to 1:10 ⁷ to that amount of metal carbonyl which is later used to actually form metal hairs. This initially low supply of metal carbonyls ensures that these spontaneously formed chains can no longer be significantly strengthened by the lateral accumulation of further ferromagnetic elementary particles and that these _ao elementary particles cannot grow into larger ferromagnetic particles before they are chain-formed.

The influence of the homogeneous magnetic field supports the magnetic alignment of the described primary coagulation chains to each other and their union to form longer aggregates. Above all the influence of the homogeneous magnetic field prevents such longer chain assemblies from being restored immediately are irregularly deformed and torn by the action of Braun's motion. Through this Measure is thus achieved that the chain units can be maintained as long as desired, while without this measure they would only be able to exist temporarily and would increase in a short time granular aggregations would be converted.

The primary chains mechanically stabilized by the magnetic field and their aggregations close longer structures move away from each other immediately after their parallel formation, since they represent micro-fine parallel magnetic bars and fill the space between the heating plate 2 and the source 3, although they were originally created in a limited zone in the thermal gradient. The reinforcement of the extremely thin primary chains is then through further deposition of metals by adding further amounts of metal carbonyls from source 3 will. It is characteristic of the process of the invention that with the primary formation the coagulation chains already have the final length of the stronger metal hairs that will emerge from them in the future can be predetermined. This can be several centimeters, for example. The length of the coagulation chains is determined by the length expansion of the source 3, as this is responsible for it is how long the cloud of metal colloids is in the reaction space from which the described Form chains. The length of the chains is limited by the walls 6 and 7 of the Reaction vessel 1 or through walls 8 and 9 in the reaction space, since it has been shown that the Coagulation chains anchor themselves very strongly to solid surfaces and that this anchorage is theirs mechanical stability can contribute significantly.

It is also characteristic of the method according to the invention that the magnetic field is only one exerts mechanical stabilization of the chains. Once a sufficient number of magnetically stabilized If there are chains in the reaction space, no new chains should be formed upon further supply made of metal compounds. According to the method according to the invention, this is achieved by that the temperature of the chains, d. H. so practically the temperature in the reaction vessel 1, before further supply of carbonyls is adjusted to the temperature required for coherent separation of the metal from this compound is required. This is how, for example, the further supply of Carbonyls from ferromagnetic metals only when the temperature of the room in which is the chains are so low that neither new chains nor larger ones can form Aggregations of metal particles that can be collected into lines by the magnetic field, but the metal attaches itself directly to the existing chains.

For this reason, the heat gradient is adjusted accordingly by lowering the temperature of the heating surface 2 reduced until the room in which the chains to be reinforced are located has a temperature which in a known manner for the coherent separation of metals from gaseous metal compounds is required. It is well known that this favorable decomposition temperature is not the temperature which would be required for complete decomposition of the metal carbonyl, but it is lower. In the case of iron pentacarbonyl, this favorable decomposition temperature is between 60 ° and 200 ° C, if The coagulation chains consist of iron crystallites because the iron decomposes iron pentacarbonyl catalytically accelerated. Those for the favorable decomposition of iron carbonyl or other metal compounds required temperature is controlled by one or more thermocouples.

The coherent deposition of the metals is understood to mean a deposition in which the during The finest metal crystallites formed on the hair surface are coherent with the deposition and firmly grown together and not just loose deposits of crystalline particles without represent a fixed relationship with each other.

For the separation of non-ferromagnetic metals from carbonyls, which have a higher decomposition temperature require, the temperature must be increased accordingly. By now running out the source 3 new amounts of metal carbonyl flow towards the chains and attach themselves to them or decompose between them, the chains continuously increase in diameter, so that they are in experience an increase in mass for a short time, the rate of growth of which is several powers of ten can make out. The metal hairs produced in this way have a homogeneous composition extremely fine single crystallites, so they are not magnetically conditioned aggregations of grain-like Metal nuclei or polycrystalline metal granules.

Since this metal hair formation according to the method of the invention in its second process stage, namely the metal deposition on magnetically stabilized chains, regardless of the use If ferromagnetic metals are used, other metals can also be used on the chains for reinforcement purposes other than the metal from which the chain is made. Except from ferromagnetic metal carbonyls these metals can also be made from other metals

thermally decomposable metal carbonyls are deposited, so that by the procedure described Metal hairs, for example from molybdenum, tungsten, etc. can be made. The production of hair by the method of the invention is not limited to pure metals, but alloys or compounds can also be deposited from the gas phase.

In Fig. 2 and 3 there is shown an apparatus in which metal hairs are produced according to the method according to the invention. F i g. 3 shows the complete device, FIG. 2 shows area A of FIG. 3 on an enlarged scale.

In Fig. 2, the heat gradient is generated from a heated, perforated metal tube 2 'to a perforated metal tube 3' arranged concentrically in this, which represents the evaporation source for the metal carbonyl. The tube 2 'is provided on its outer jacket with heating rods 10, which leave gaps between them for the gas to exit from the reaction space V and have an insulated electrical resistance heater in their interior. The heating rods 10, which are connected in parallel or in series, are surrounded in a gas-tight manner by a further pipe jacket 11 which opens into the gas discharge pipe 12. Inside the perforated tube 3 'serving as an evaporation source is a tube 13 which is heated to over 102 ° C. by means of a thermostatic fluid and on which a helix 14 rests. The thermostat liquid is supplied through the pipe 13 'and flows in countercurrent through the space between the pipes 13 and 13'. Liquid iron pentacarbonyl seeps down on the helix 14 in a spiral path and is fed through the tube 15 into the space between the heating tube 13 and the perforated tube 3 '. The reaction space V is closed at the top by a movable piston 16 which is not flush with the wall of the heating tube 2 'and therefore allows inert gases to enter the reaction space 1'. The piston 16 forms a one-sided adhesive point for the chains of coagulating ferromagnetic elementary particles to be produced later and, after the thread production has been completed, serves to eject the finished metal hairs down into the collecting vessel 17, which is shown in FIG. 3 is shown. This collecting vessel can be removed from the apparatus. Before this, the fine metal hairs are flooded with an inert gas through the feed 18 in order to protect them from spontaneous oxidation. In Fig. 3 also shows a geared motor 19 which moves the piston 16 up or down via a shaft 20. With 21 and 22 lines for the supply of inert gas to the reaction chamber 1 'are designated.

The operation of this arrangement is as follows. First, lines 21 and 22 in FIG. 3 inert gases supplied to flush out the reaction chamber V , which gases flow through line 12. Then a small amount of iron carbonyl is fed in through the feed pipe 15, which evaporates on the heated coil 14 and penetrates in vapor form through the perforated pipe 3 'into the reaction space 1' and here between the pipes 2 'and 3' generates metal colloids in an annular zone, which immediately afterwards spontaneously form into coagulation chains. These coagulation chains are stabilized by a homogeneous magnetic field running in the direction of the axis of the tube 2 ', which is generated in a known manner by a magnetic coil, until after the temperature in the reaction chamber 1' has been lowered, further iron carbonyl through the tube 15 in F i G. 2 is fed or another thermally cleavable metal carbonyl, z. B. Nickel tetracarbonyl. The metal carbonyl is then continuously evaporated in large quantities from the source 3 '

ίο and decomposes on the coagulation chains, while additionally through the supply pipe 15 or through the supply pipes 21 and 22 in FIG. 3 small quantities of inert gases flow in, the quantity of which is such that it cannot generate any turbulence, and which should above all generate a slight overpressure in the reaction chamber V in order to reliably prevent the ingress of oxygen. After the primary coagulation chains have been sufficiently strengthened, the metal threads formed are removed by the piston 16 in FIG. 2 ejected into the collecting vessel 17, which is shown in FIG. 3 is shown.

The evaporation of the thermally decomposable metal compound for the purpose of strengthening the Chains by metal deposition directly in the reaction space has the great advantage that relative Vaporize large amounts of the metal carbonyls per unit of time and cause them to decompose can. Due to the evaporation of the carbonyl within the reaction chamber, not only liquid thermally decomposable, but also solid, in an inert liquid, e.g. B. oils, thermally dissolved decomposable metal carbonyls, such as. B. Molybdenum carbonyl in the vapor state directly the Decomposition reaction are fed.

The extremely finely crystalline metal hairs produced by the process according to the invention have high strength. These metal hairs are therefore particularly suitable for the production of sintered bodies, because they do not break during pressing like other inhomogeneously structured fibers, but retain their hair-like or thread-like structure even after sintering and shaping. Likewise These hairs are suitable because of their high strength and their large ratio of diameter to length to the known embedding in a matrix. According to the invention Process produced metal hairs can also be done by cold deformation, for example processed into compact materials by cold rolling or pressing, or cold welding will. The manufacture of metal hair by the method of the invention also includes the generation of metal hairs resulting from the simultaneous deposition of different carbonyl forming metals as well as from the simultaneous deposition of metals and non-metals. During the formation of the metal hairs by strengthening the chains as a result of metal deposition can use non-metallic substances continuously or intermittently at certain time intervals to be deposited with. On the other hand, it can also be intermittent during the deposition of metals Superficial oxidation, nitration, etc. take place at certain time intervals.

The storage or zone-like deposition of non-metals is among other things. brought about for the purpose a growth of the crystallites of the poly-

! crystalline metal hairs at high temperatures suppress.

Claims (11)

Patent claims: 1. A method for producing polycrystalline metal hair, of predeterminable length and thickness under Metallcarbonylzersetzung, characterized in that first carbonyls ferromagnetic metals in an oxygen-free space in the smallest amounts of the order of 10 ~ ⁴ to 1O ^-10 moles per cm ³ of this space against a temperature gradient generated in this room, the metal atoms released by the thermal decomposition of the carbonyls agglomerate to form tiny crystals, which are generated by a homogeneous magnetic field ■ arranged in aggregation chains parallel to each other and to the lines of force of the magnetic field which are mechanically stabilized by the magnetic field, whereupon further into the room Carbonyl vapors of ferromagnetic and / or paramagnetic metals fed in and against the temperature gradient through the room with simultaneous equalization the temperature of the aggregation chains for a coherent separation of these Metals required temperature until the metal hairs have the desired thickness. 2. The method according to claim 1, characterized in that metal mixtures from carbonyl mixtures are deposited on the aggregation chains. 3. The method according to claim 1, characterized in that on the aggregation chains Different metals are deposited one after the other. 4. The method according to any one of claims 1 to 3, characterized in that in the carbonyl atmosphere dispersed non-metals or metal compounds simultaneously with the Metals are deposited on the aggregation chains. 5. The method according to any one of claims 1 to 4, characterized in that during the Deposition of a layer on the aggregation chains at the same time a chemical treatment, z. B. oxidizing, carburizing, nitriding and the like., Is carried out or the chemical treatment is interposed when several layers are deposited. 6. The method according to any one of claims 1 to 5, characterized in that the metal carbonyls, especially solid, sublimed or difficult to evaporate carbonyls, in a hate Solvents are used. 7. The method according to one or more of the preceding claims, characterized in, that the thermally decomposable carbonyl compounds in the liquid state within of the reaction chamber arranged evaporation source are supplied. 8. Device for performing the method according to one or more of the preceding claims, characterized by an airtight reaction vessel (1, V), the interior of which is provided with an externally fed porous carbonyl vapor source (3, 3 ') and a gas-permeable heating surface (2, 2 ') , behind which there is an outlet for the inert purging gases and the carbon monoxide formed during the decomposition of the carbonyls, the space between the carbonyl vapor source (3, 3') and the heating surface (2, 2 ') being the decomposition zone which forms carbonyls, and by two magnetic poles (4, 5) which are arranged so that their lines of force run parallel to the heating surface (2, 2 ') . 9. Apparatus according to claim 8, characterized in that the carbonyl vapor source from a perforated distribution pipe (3 ') heated to the evaporation temperature of the carbonyl and a heating tube (13) arranged concentrically in it, on the outer wall of which there is a Helix (14) is attached that the space formed by these two tubes (3 ', 13) at its upper end a feed line (15) for the dripping onto the coil (14) and thereby evaporating carbonyl has that the distributor pipe (3 ') concentrically from a perforated, heating tube heated to a temperature above the decomposition temperature of the carbonyl (2 ') is surrounded, which in turn by a jacket pipe opening into a gas discharge pipe (12) (11) is hermetically enclosed, and that in the annular space forming the carbonyl decomposition zone between the distributor pipe (3 ') and the heating pipe (2'), which is hermetically sealed at its top The end is provided with inlets (21, 22) for the inert purge gases and the under the influence of a homogeneous magnetic field running parallel to the axis of the heating tube (2 ') stands, an upward and downwardly movable annular piston (16) is arranged, which as Adhesion point for the forming metal hairs and for pushing the finished metal hair into one at the lower end of the device attached collecting vessel (17) is used, the collecting vessel (17) with a feed (18) for an inert gas to protect the accumulated metal hairs against Spontaneous oxidation is provided. 10. Use of the according to the method according to one or more of claims 1 to 7 manufactured metal hairs for the production of sintered metals. 11. Use of the according to the method according to one or more of claims 1 to 7 manufactured metal hair for the production of materials by cold forming and / or Cold welding. Considered publications:
U.S. Patent No. 2,726,951. 1 sheet of drawings 609 660/338 9.66 © Bundesdruckerei Berlin